1. Field of the Invention
The present invention related generally to audio processing, and more particularly to producing an acoustic field having a target spatial pattern.
2. Description of Related Art
Various types of audio devices such as cellular phones, laptop computers and conferencing systems present an acoustic signal through one or more speakers of the audio device, so that one or more acoustic waves are generated, which when superimposed form an acoustic field proximate to the audio device. The acoustic field formed by the generated acoustic waves can then be received by an ear of a person who is an intended listener, so that the acoustic signal is heard.
However, typically the acoustic waves originating from the audio device will also travel in other directions within the near-end acoustic environment than toward the intended listener, and may combine to form an acoustic field having significant energy in regions other than where the intended listener is situated. This can be undesirable for a number of reasons. For example, other people within the near-end acoustic environment may also hear the acoustic signal, which can be annoying to them. In addition, in some instances the acoustic signal may contain information intended to be heard only by the intended listener, such as a user of the audio device. Thus, transmitting the acoustic wave throughout the near-end acoustic environment may limit the usefulness of such audio devices in certain instances.
In addition, transmitting the acoustic wave throughout the near-end acoustic environment can result in the problem of acoustic echo, which is a delayed and distorted version of an original sound reflected back to its source. In a typical conversation, a far-end acoustic signal of a remote person speaking at the “far-end” is transmitted over a network to an audio device of a person listening at the “near-end.” When the far-end acoustic signal is presented through the loudspeaker of the audio device, part of this acoustic wave may be reflected via an echo path to a microphone or other acoustic sensor of the audio device. This reflected signal may then be processed by the audio device and transmitted back to the remote person, resulting in echo. As such, the remote person will hear a delayed and distorted version of their own speech, which can interfere with normal communication and is annoying.
It is therefore desirable to provide systems and methods for producing an acoustic field which can overcome or substantially alleviate problems associated with transmitting the acoustic signal to the intended listener, such as those described above.